They're going to see Leicester play in Seville so direct flights are now pricey. Arriving into Terminal 1 Madrid. Seat61 was very informative and indeed the Renfe site is very fiddly. I've found the Loco2 site easy to check prices and according to Seat61, print at home tickets from Loco2 includes free suburban transfer using Cascanias from T4 to Atocha.
Found very good prices on Preferente 1st Class non flexible, which I believe offers an inclusive meal with wine on the AVE to Seville but no 1st Lounge access. Their flight arrives Madrid T1 at 1015, do you reckon the 1200 AVE from Atocha is too tight and the 1330 a safer bet? If booking Spanish tickets on Loco2, do I need to enter passport numbers for all passengers?
You ask difficult questions!
With a following wind you could just get the 1200, either using the Metro from T1 or the 1057 Cercanias from T4 (after using the inter-terminal transfer bus from T1 to T4 - this goes miles on the endless link roads and stops everywhere en route).
But you are reliant on EasyJet (or whoever) being punctual and getting through passport control without delay.
Personally, I'd aim for the 1330.
This is an Alvia (dual gauge, probably Talgo) service, not AVE, runs through the gauge changer approaching Seville and goes through to Cadiz on the broad gauge.
It's a few minutes slower than the dedicated AVE trains.
As it happens I used this train (from Cordoba) last year.
There will be a bar car, but no free meals I think.
I can see a 34.60 Preferente fare on Renfe for the 1330, but cheapest shown on the 1200 is 58.50.
If you get an hour or so to wait at Atocha, there are plenty of eating places and a tropical garden to explore, all under cover.